Welcome! Definitely feed in the enclosure. The biggest issue feeding outside is deciding when to put your snake back in. Mine like to grab a drink of water sometimes and curl up over the belly heat or in a hide. I would not want to handle them after feeding and you risk stressing them which could potentially lead to regurgitation which is not good.
i’ve used Aspen bedding for 2 years and never had a problem. Yes, your noodle will eat a mouse if hungry but as mentioned above, if your snake is already onto rats try to leave it at that.
Enjoy your new family member!